The invention relates to an impregnated foil for wrapping the tips of hair (hair-tip paper) for use before permanent wave treatment in hair-care establishments.
To produce a permanent deformation of human hair, curlers are needed in addition to a reducing and oxidizing agent. The hair is rolled up along its longitudinal axis from the hair tips to the root region near the scalp. By the multiple wrapping of the hair around the roller, the hair tips necessarily assume a smaller curl than the hair in the root region. The small-curl tip deformation, however, presents a hindrance to the hairstyling and is therefore undesirable. A complicating factor is that the hair in the undamaged (original) state of the root region still has a more closed cuticle. For this reason, the root region is more resistant compared to the tip region which is months older and as a result of combing, washing, bleaching, dyeing or waving and of environmental influences gradually becomes more and more brittle and porous.
The aforeindicated drawbacks concerning the hair tips cause the hair""s structure and ability to be styled to deteriorate.
Repeated attempts have been made to achieve uniform waving results and a tip protection/structure balance by means of permanent-wave pretreatment agents (see, for example, WO-A 97/09028) or by means of hair-tip paper impregnated with acids (see, for example, DE-A 33 11 292 and DE-A 1 492 007) or with oils (see, for example, DE-A 42 36 726). Permanent-wave pretreatment agents are sold as liquids or gels. It has been found in practice that application and dosing problems cannot be avoided with either of the two forms of consistency. A hair-tip paper impregnated only with acids or only with oils shows low efficacy in terms of wave and structure balance.
The object of the present invention is to avoid the aforesaid overcurling effect by means of a new foil so that during the period of exposure to the waving preparation the effect on the lengths and tips is gentle compared to that of the current methods, the known drawbacks thus being avoided. As a result, the hair structure is less damaged, and despite tighter winding the lengths and tips are given a comparable wave radius, like that in the root region near the scalp.
Surprisingly, we have now found that by use of a foil for hair-tip wrapping which has been impregnated with an aqueous preparation containing
a) from 20 to 70 wt % of a lipophilic substance,
b) from 1 to 25 wt % of an emulsifier and
c) from 0.5 to 15 wt % of an organic acid
it is possible to prevent the undesirable, too small-curled waving at the hair tips. At-the same time, the sensitive part of the hair is protected by the natural oils, and the acids prevent excessive swelling.
Foils such as hair-tip paper for permanent waving are in themselves known. They usually consist of wet-strength paper, for example long-fiber, silk or rice paper. However, the foil can also consist of some other absorbent material, for example of nonwoven material, cotton fabric or mixed fabrics of synthetic and natural fibers.
The lipophilic substance is preferably contained in the aqueous preparation in an amount from 40 to 60 wt %. Said substance is preferably a natural oil or wax selected from among physiologically well tolerated, particularly unsaturated, natural, hydrophobic oils or waxes. Particularly preferred is a vegetable oil such as, for example, jojoba oil, avocado oil, sunflower oil, wheat germ oil, peach kernel oil, mink oil, castor oil, sesame oil, peanut oil, rape oil, cottonseed oil or soybean oil. Other suitable physiologically well tolerated natural oils and waxes are montan wax, ozocerite, vaseline and paraffin or synthetic oils , such as, for example, silicone oils.
Preferably, the emulsifier is contained in the aqueous preparation in an amount from 2 to 15 wt % and particularly from 3 to 10 wt %. Said emulsifier is preferably selected from among compounds of the following group ethoxylated with 2 to 200 ethylene oxide units: fatty acids, fatty amides, fatty amines or fatty alcohols, each with 6 to 30 carbon atoms, and fatty esters with 6 to 30 carbon atoms in the fatty acid radical. Hydrogenated castor oil ethoxylated with, for example, 7 ethylene oxide units (for example, Arlacel(copyright) 989 supplied by ICI) and hydrogenated castor oil ethoxylated with 40 ethylene oxide units (for example, Cremophor(copyright) RH40, supplied by BASF) are particularly well suited emulsifiers.
Preferably, the organic acid is contained in the aqueous preparation in an amount from 1 to 7 wt % and particularly from 2 to 6 wt %. Said acid is preferably a hydroxycarboxylic acid or an aldehyde carboxylic acid or ketocarboxylic acid. Examples of suitable acids are glyoxylic, citric, ascorbic, lactic, tartaric, acetic, aconitic, acetylenedicarboxylic, ethylenedicarboxylic, ethylenemaleic, xcex1-ethylcrotonic, i-amylmaleic, angelic, n-butylfumaric, n-butyl- or isobutylmaleic, citraconic, crotonic, fumaric, trans-glutaconic, isopropylmaleic, itaconic, maleic, mesaconic, a-methylitaconic, cis-xcex1-methylglutaconic, trans-xcex1-methylglutaconic, propiolic and cinnamic acid.
The aqueous preparation preferably contains from 30 to 60 wt % of water. In addition, it can optionally contain additives, such as stabilizers, buffers, fragrance oils, dyes as well as hair-conditioning and hair-care constituents such as, for example, cationic polymers, lanolin derivatives, cholesterol, pantothenic acid and betaine.
Said constituents are used in amounts usually employed for such purposes, the fragrance oils and dyes, for example, in amounts from 0.01 to 1 wt %, the buffers in a total amount from 0.1 to 10 wt %, the stabilizers and the hair-conditioners and hair-care agentin an amount from 0.1 to 5 wt % each.
Comparative tests on subjects for whom the hair-tip paper was impregnated only with oils or only with acids gave clearly poorer and unsatisfactory results. Thus, these tests confirm very impressively the above-described action.